Research

softpinna: Non-Rigid Registration for the Calculation of HRTFs

Duration: 01.07.2019 to 31.03.2023

Millions of people use headphones everyday for listening to music, for watching movies, or when communicating with others. Nevertheless, the sounds presented via headphones are usually perceived inside the head and not at their actual natural spatial position. This limited perception is inherent and results in unrealistic listening situations.

When listening to a sound without headphones, the acoustic information of the sound source is modified by our head and our torso, an effect described by the head-related transfer functions (HRTFs). The shape of our ears contributes to that modification by filtering the sound depending on the source direction. But the ear is very listener-specific – its individuality is similar to that of a finger print, and thus HRTFs are very listener-specific. When listening to sounds via headphones, the listener-specific filtering is usually not available. One of the main reasons is the difficulty in the process of acquisition of the ear shape of a person, and thus in calculation of listener-specific HRTFs.

Thus, in softpinna, we worked on the development of new methods for a better acquisition of listener-specific ear shapes of a person. Specifically, we investigated and improved the so-called "non-rigid registration" (NRR) algorithms, applied on 3-D ear geometries calculated from 2-D photos of a person’s ears. The improvement in the quality of the 3-D ear geometries acquisition helped computer programs to calculate the listener-specific HRTFs, thus enabling the incorporation of listener-specific HRTFs in future headphone systems providing realistic presentation of spatial sounds. The new ear-shape acquisition method is able to reduce the technical requirements for accurate calculation of listener-specific HRTFs.

This project was done in collaboration with Dreamwaves GmbH. It was supported by the Bridge Programme of the FFG. 

The following publications were done within softpinna: 

  • Pollack, K., Majdak, P., and Furtado, H. (2023). “Combination of Photogrammetry and Non-Rigid Pinna Registration for the Calculation of Personalised Head-Related Transfer Functions,” in the proceedings of the 10th Forum Acusticum, Turin, Italy. 
  • Pollack, K., Majdak, P., and Furtado, H. (2023) “Application of non-rigid registration to photogrammetrically reconstructed pinna point clouds for the calculation of personalised head-related transfer functions”, in Fortschritte der Akustik - DAGA 2023, p. 1094 – 1098, Hamburg, Germany.
  • Pollack, K., Kreuzer, W., and Majdak, P. (2022). “Modern Acquisition of Personalised Head-Related Transfer Functions: An Overview,” in Advances in Fundamental and Applied Research on Spatial Audio, edited by B. Katz and P. Majdak, (IntechOpen, London UK). DOI: 10.5772/intechopen.102908.
  • Pollack, K., Majdak, P., and Furtado, H. (2022). “Non-rigid registration of photogrammetrically reconstructed pinna point clouds for the calculation of head-related transfer functions,” presented at the Vienna Talk, Vienna.
  • Pollack, K. and Majdak, P. (2022). “Nichtrigide Anpassung von Punktwolken zur Berechnung von personalisierten Head-Related Transfer Functions,” presented at the 48th German Convention on Acoustics (DAGA), Stuttgart, Germany.
  • Pollack, K., Majdak, P., and Furtado, H. (2021). “Parametrisation of Pinna Geometry,” presented at the Dreiländertagung der Medizinischen Physik (Joint Conference of the ÖGMP, DGMP & SGSMP) (presented online).
  • Pollack, K., Brinkmann, F., Majdak, P., and Kreuzer, W. (2021). “Von Fotos zu personalisierter räumlicher Audiowiedergabe,” Elektrotech Inftech, 138, 250–255. DOI: 10.1007/s00502-021-00891-4.
  • Pollack, K., Majdak, P., and Furtado, H. (2021). “Evaluation of Pinna Point Cloud Alignment by Means of Non-Rigid Registration Algorithms,” in the proceedings of the 150th Convention of the Audio Engineering Society (AES), Convention Paper 10475 (presented online).
  • Pollack, K. and Majdak, P. (2021). “Evaluation of a parametric pinna model for the calculation of head-related transfer functions,” in Immersive and 3D Audio: from Architecture to Automotive (I3DA), 1–5. DOI: 10.1109/I3DA48870.2021.9610885.
  • Pollack, K., Majdak, P., and Furtado, H. (2020). “A Landmark-Based Parametric Pinna Model For The Calculation of Head-Related Transfer Functions,” in the proceedings of the 9th Forum Acusticum (presented online). 
Hearing
Numerics

Team